Device for the cleaning of sight glasses allowing inspection of high vacuum rooms



May 15, 1956 M. AUWARTER DEVICE FOR THE CLEANING OF SIGHT GLASSES ALLOWING INSPECTION OF HIGH VACUUM ROOMS Filed March 17, 1951 77):: 3/1 venzars:

United States Patent DEVICE FOR THE CLEANING F SIGHT GLASSES ALLOVgING INSPECTION OF HIGH VACUUM ROOM Max Auwiirter, Balzers, Liechtenstein, assignor to Alois Vogt, Vaduz, Liechtenstein Application March 17, 1951, Serial No. 216,231

Claims priority, application Switzerland March 22, 1950 2 Claims. (Cl. '15--255) When melting and casting certain materials, and especially when melting and casting metals and their alloys in a high vacuum, an important improvement in quality of the material treated in such manner is attained with the rise of the vacuum as against the degree of evacuation used and feasible up to now. Hence there is a tendency to raise the vacuum to a value of 10" mm. Hg and to increase the vacuum even further. But with these low pressures there occurs a heavy evaporation of the melted materials, whereby their vapors are inclined to condense upon the sight glasses thru which the examination of the melting and casting phenomena occurs. In many cases the melting charge is even deliberately overheated, in order to expell undesirable material components-impurities or the like-be it inform of vapors, or gases, or in another way. In consequence heavy deposits of solid matters settle, on the observation glasses, forming light absorbent layers which deprive the observer of the sight of the materials inside the high vacuum vessel.

In order to remove these difiiculties it is already known to arrange exchangeable protection glasses in front of the peepholes, so that it should be possible, when a protection glass becomes entirely coated and tarnished, to bring the next glass in its place which will allow renewed observation for a further while. But without regard to the fact that the number of protection glasses cannot be increased ad libitum, so that after some time all the protection glasses available will be coated, rendering any further observation impossible, these precautions will prove entirely useless as soon the subprcssures used up to nowand previously alluded toare left, and one enters the domain of the high vacuum beyond the limit of approximately '10- mm. Hg already mentioned. For now the rate of vaporization and the quantities of vapor and deposits thereby developed increase so greatly that the necessary observations cannot be secured any longer by these known means.

It seems obvious to try and remove the difliculties, which arose in such a manner, thru means which eliminates the necessity for breaking thru the boundary wall of the high vacuum room. However it has turned out that the problem above presented can not be solved in this way.

I have now found that a completely satisfactory observation of high vacuum chambers of the kind above referred to can be eifected through sight glasses, allowing inspection of high vacuum rooms where deposits of light absorbent solid matter coats have been created, which, following the present invention is characterized by the fact that mechanical forces are exerted to shove off said deposits from inside. In such a manner the sight glasses can be kept sufficiently clear and transparent for observation, whereby said procedure may in its most simple form consist in brushing off said deposits.

The drawing shows by Way of example the illustration 70 of a device serving to carry out such a method, whereby Fig. 1 represents said device in elevation, whereas Fig. 2 corresponds to a partial top view, and a partial cut thru line IIII of Fig. 1.

In both schematically drawn figures 1 indicates the boundary walls of high vacuum room 2. The upper closing wall shows at 3 a headpiece serving to take up the observation glass 4 and is sealed by a packing 5 of appropriate design against the high vacuum in room 2. A marginal disk 6, together with the clamping bolts 7, attends to the necessary bearing and sealing pressure. A protection glass 8 is arranged in front of sight glass 4 and in direction of room 2; said protection glass is exchangeably inserted into support 9. Operating shaft 10, which at 11 turns into a handle, likewise passes thru headpiece 3. A packing 12, which can be executed in the form of a high vacuum resistant seal, makes shaft 10 perfectly tight as against room 2.

The shaft end 10 bears with the aid of set screw 13 a bushing 14, which at 15 turns into a sector-shaped disk which serves as a screen. At least one edge of screen 15 is trimmed with bristles 16.

The brush formed in such a manner may suitably consist of metal bristles.

The mode of operation of the device will be evident from the foregoing.

The figures of the drawing show the brush 16 just at the moment'when it joins the observation glass 8 and shoves offor brushes oifits solid coating. This can be done by appropriately swinging the handle 11 to and fro. When the observation which thereby has been rendered possible is over, the part of screen 15 not covered with bristles is pushed under glass 8, so that this latter should be protected as much as possible from the danger of being coated. As shown in the drawing, the sector-shaped screen is of such angular extent that it can cover completely the glass 8. Nevertheless, if such a layer has been freshly formed before the next observation should take place, said coating will be easily removed by operating the bristles 16.

It lies in the essence of the invention under consideration that many variants of its underlying principle are feasible. For instance a mechanical movement of the brush can take place instead of said brush being actuated by hand.

What I claim is:

1. The combination with a high vacuum chamber which in use is adapted to contain hot vapors of light-absorbing solid matter which condense and precipitate on the walls thereof, of means for allowing inspection of the interior of said chamber, comprising a transparent window in a wall of the chamber, a cleaning element arranged within said chamber to sweep over the window to remove condensed matter therefrom, and means for actuating said cleaning element, said actuating means comprising a shaft arranged'to swing the cleaning element parallel to the plane of the window, said shaft passing through the wall of the high vacuum chamber, a high vacuum resistant packing between the shaft and wall, and a sector-shaped plate secured to the shaft and normally disposed'in front of the window to minimize the quantity of vapor particles impinging on the window, said cleaning element being disposed on the plate to one side thereof and between the plate and the window.

2. The combination with a high vacuum chamber which in use is adapted to contain hot vapors of light-absorbing solid matter which condense and precipitate on the walls thereof, of means for allowing inspection of the interior of said chamber, comprising a transparent window in a wall of the chamber, a cleaning element arranged within said chamber to sweep over the window to remove condensed matter therefrom, means for actuating said cleaning element to move the same across the face of the windowfpa rallehto the plane'of the window and in Contact therewith,..and awplate normallydisposed in frontofthe Window to shield the same and thereby minimize the quantity of vapor particles impinging on the window, said platesbein'g. movabie by said :actuating means from: in front of the window to expose the latter, said-c1eanii1g element being-;disposed bet-ween the plate and thewwindow,

References Cited in the file of this patent UNITED STATES PATENTS 737,439 Michie Aug. 25, 1903 1,072,832 Daines Sept. 9, 1913 2,423,604 McCord July 8, 1947 FOREIGN PATENTS 7 25,497 Sweden 2; of :1908 378,859 Italy 'of-1"940 

